In a portable system utilized for the control of ink flow to an inkjet printhead, it is necessary to ensure that the printhead continues to function and receive an ink supply in the presence of movement of the printhead due to its portability. Examples of portable systems include the recently filed PCT Application Nos. PCT/AU98/00550 and PCT/AU98/00549 filed by the present applicant.
For example, when utilized in a camera system with an internal printer, it is desirable to provide for proper operation and ink flow and the presence of movement of the portable camera system. Further, it is desirable to provide for such a system as cheaply and efficiently as possible. This is particularly the case where the camera is utilized in a portable manner whilst printing.
Most commercially used inks have properties similar to water. Accordingly the viscosity of ink will substantially fluctuate with temperature. When the printer is not in use, the ink in the nozzle chambers will cool to ambient and its viscosity is higher than during printer operation. When the printer first activates after a period of inactivity, the viscous ink is more difficult to eject. Many printers will compensate for this by briefly operating the actuators in an overdrive mode until the printhead is at its normal operating temperature. However, reducing the power consumption of printheads is an overriding consideration because removing the heat generated by the actuators is a fundamental issue for inkjet printing. A low power printhead will have little or no need for a cooling system but has a reduced ability for overdrive. As the power consumption of the printhead is reduced, the operating range of the ejection actuators needs to increase in order to overdrive. Such a broad operating range is difficult and impractical.